Method and apparatus for radio beacon course and quadrant identification



Feb. 26 1935. F. w. DUNMORE 'METHOI) AND APPARATUS FOR RADIO BEACON COURSE AND QUADRANT IDENTIFICATION Filed Feb. 4, 1935 4 Sheets-Sheet 1 mvI Feb. 26 1935. w DUNM QRE v 1,992,927

METHOD AND APPARATUS FOR RADIO BEACON COURSE AND QUADRANT IDENTIFICATION File'd Feb. 4, Q1955 4 Sheets-Sheet 2 T0 BEACON nonuua me "ruse 1000-MOD.

Feb. 26, 1935. D DUNM-ORE 1,992,927

METHOD AND APPARATUS FOR RADIO BEACON COURSE AND QUADRANT IDENTIFICATION Filed Feb. 4, 1935 4 Sheets-Sheet 3 TO IOOO MODULATION Feb. 26 1935. w DUNMORE 1,992,927

METHOD AND APPARATUS FOR RADIO BEACON COURSE AND QUADRANT' IDENTIFICATION Filed Feb. 4, 1935 4 Sheets- Sheet 4 To 6 on. 065562. MODULATION e5- 967;- 1000- |ooo- Patented Feb. 26, 1935 METHOD AND PATENT; OFFlCE BEACON COURSE,AND' QUADRANT IDEN- j TEFICATION ,Francis W. Dunmore; Washington, as-

signor to the Government of the United States, as representedby the Secretary of Commerce Application February 4, 193$,Serial No. 655,190

Claims. 101. 250 -11 (Granted under the act of March 3, .1883, as v I amended April 30, 1928; 3'70 "0. (3. 757) i i The invention.describedfherein may be manufactured and used by orrior the Government of the United States for governmental purposes only Without the paymentof any royalty thereon.

My invention relates to an improvement in the radio beacon of thevisual aural orcombined visual andaural types in Whicha pilot when lostis given an identification signal which tells, him' which of the four quadrants he may be in or which i of the four courses he may be on, or whether or not he has passed by the beaconastation.

,With the: radio rangesystem as now used, if a pilotshould become .lost due to some emergency Whichmight divert his attention from the radio beacon course indications, especially when near the-radiobeacomit becomesa very difilcult matter for him to reorient himself, especially if he has passed the -beaconnimthe meantime. His course indicationsumay show. him to be in one of. two quadrantsor onany one of four courses, he does not known which. Only'by a process of assump-. tion and a laborious method of flying over a considerable distance involving; on the average an hours; time can he orient him-self. -A radio'beacon should not only function to keep a pilot from getting lost but it should also provide means whereby in case he does become lost :be may readily orient himself and get on a. known course; This invention describes such a means, requiring but slight modifications at the radio beacon and no extra equipment on the airplane.

- In one form of my invention; identification signals sent in 'difierent directions andgdifierently coded are transmitted from the radio beacon. 35 In the case of thevisual type of radio beaconthes'e'signals are; received aurally without'interruption'to the beaconservice, while with the aural beacon, thebeacon service is interrupted for four or five seconds every two or three minutes. *From 40" the relative intensities of the coded identification positedirectionsand along the'line of one of the.

; transmissionlline; type of, antenna systems. a

Fig. 2. shows thecircuit arrangement for transmitting the two cardioids as shown in Fig. 1.

. Fig; 3 shows another arrangement in which four cardioids are transmitted consecutively each alongthedirectionof one of the IL antennas.

. Fig. 4 shows a diagram of oneform of apparatus which utilizes my method of transmitting the four cardioids as shown in Fig. 3. v 1 Fig. 5 shows the circuit arrangement for the transmission of the four cardioids indirections other than along the line of direction of the transmission line. type of antenna system. 1 a

In Fig. 1 which shows one formof my invention, 13 and 14 represent the usual figure-of-S' transmission characteristic for giving the visual or aural type radio beacon courses 9 l0 11- and l2. The transmission for producing these courses may preferably takeplace from the transmission line type of antenna system consisting of cage antennas- 1, 2, 3' and 4; and transmission lines-5, 6,

'7 and8. Thesaidtransmissionlinetype or; antenna system was more fully. described in the Bureau of Standards Journal of Researchf, vo1. 10,'Jan- I nary l933,-which was also republished in the Eureau of; Standards Research Paper ,No. .513, en-

'titled iThecause an elimination of night effect in radio range beacon reception by Harry Diamond see particularly under subtitle V. Trans: mission-LineAntenna Systemifipp. 23-33 of said research paper) By properly phasing thecurrentsin antennas l and 3 the energy radiated may be made to cancel in one direction. and addin the other, giving a cardioid transmission characteristic 16. This is done by introducing. the proper phasing sections in the proper place in'the transmission lines feeding the vertical antennas. The positions of these phasing sections in the transmission lines are altered by means of suitable re lays, such alterations producingthe .cardioid signals and reversing the direction of their transmission. A. code signal, consisting of one ,dot

is. sentwhe'n this cardioid is transmitted. 'f'By' a.

reversalfof this phasing, .the energymay be radiated in the opposite direction giving cardioid 15. A code signal of two dots is sent when this cardioid is transmittedv l 7 Referring to Fig. 1, during the transmissions of the dot and double dot cardioid position identification signals, the beacon coursesignals 13 andfl' are interruptedin the case of the aural type beacon for a period *of four lseconds every two orthree minutes and in the case of the visualsystem' the interruption is only for the time interval of each quick dot and as the dots are of veryshort duration, the interruption is hardly perceptible on the pointer type course indicator with proper damping and filtering, and not objectionable in the case of the reed indicator. Every two or three minutes the reeds will both drop in amplitude about for the inidentification cardioid signal is heard he gets two dots noticeably louder than the one dot in the ratio of 0Q to OP, showing him he is in the N or 86 quadrant north of the beacon and not in the similar quadrant south of the beacon.

2. An on course indication is obtained from the beacon'signal. Which of the four courses isthe pilot on? When the positionsignal is heard, the two dots are very loud and the one dot hardly audible. The pilot must therefore be on course 10. If he had heard the one dot loud and the two dots very weakly, he would have been on course 12. Had the one and two dots been of the same or nearly same intensity, he would have been on course 9 or 11. To determine which of these he is on, he gets his compass heading when flying on the course and notes that it is in a southeasterly direction. He deviates off course to the right and obtains a pronounced N or 86 cycle signal. He must therefore be flying southeast on course 11 since if he was on course 9 and flying southeast and deviated to the right, he would obtain a pronounced A or cycle signal;

Even when lost in an A (65' cycle) or N (86 cycle) quadrant, the pilot can tell which of the two adjacent courses he is nearest by the relative strength of the dot and two dot signals. For example, if a pilot getting a strong A or 65 cycle signal hears the one dot about twice as loud as the two dots, in the ratio of OT to OR, this shows him he is somewhere in the region of the line ON near course nine and not in the region of the line OL near course twelve 50' along. which line he would have heard the one dot very loudly and the two dots very weak in the ratio of 0V to OU.

Another. advantage of this invention is that the pilot may determine that he has passed over the beacon when flying along courses 10 or 12 since the one dot changes to two dots when the beacon is passed in flying from course 12 to'10, and the two dots change to one dot when the beacon is passed when flying from course 10 In Fig. 2 is'diagrammatically shown an apparatus which utilizes my method for transmitting the two cardioids shown in Fig. 1. 17 is a motor driving the one dot sending disc 18 and 2 dot disc 19. 20 and 21 are contacts for making the dots, 22 is a timing switch for sending the cardioids as often as desired. 23 is a double-pole double-throw relay operated by contacts 20 and 21 and serves'to take the.65cycle-86 A;-cycle modulation 01f of a transformer 24 supplying the beacon amplifiers and puts on 1,000 cycle during the time of the cardioid transmissions.

The transformer 24 is of the standard type and serves to modulate the outputs of the two amplifier legs in the radio beacon transmitter,

one leg supplying radio frequency power modulated at 65 cycle and the other radio frequency power of the same radio frequency but modulated at 86 cycles, both supplies of power. entering the antennas through coils 43 and 44 and their attached transmission lines. 25, 26, 27 and 28 are the vertical antennas of the transmission line type of antenna system. These correspond to antennas 1, 2, 3 and 4 respectively, in Fig. 1. 39, 40, 41 and 42 are the coupling units to antennas 25, 26, 27 and 28 respectively. 29, 30, 31 and 32 are phasing sections in the transmission lines for producing the figure-of-8 transmission for the beacon course signals. 33-34 and 35-36 are parts of 29 and 31, respectively, which are thrown into the transmission line feeding antenna 25 or the transmission line feeding antenna 27 by means of open-circuit type doublepole single-throw relays 37 and 38. 37 and 38 are for producing the cardioid transmissions. 43 is a secondary supplying power to antennas 26 and .28 from a source of radiofrequency 43a; and. 44 supplies antennas 25 and 27 from a source of radio frequency 44a. 43 and 44 are coupled to the beacon transmitter output through a suitable goniometer. 45 is a single-pole single-throw relay which short-circuits coil 43 rendering antennas 26 and 28 inoperative during the cardioid transmissions from antennas 25 and 27.

With contacts 20 and 21 open, relay 23 is closed on the back contacts putting 65 and 86% cycle modulation on. the beacon amplifiers. 37, 38 and 45 are open and relay 46 is closed. When contact 20' closes, relay 23 closes to the right putt-ing 1000 cycle on the modulating amplifiers, relay 45 closes preventing any radiation from antennas 26 and 28, relay 46 opens taking the radio-frequency power supply from the center. of the transmission lines supplying antennas .25 and 27, and relay 37 closes connecting secondary 44 to the opposite side of phasing coils 33 and 34 thus sending a dot cardioid transmission characteristic in the direction of antenna 25. When contact 21 closes, relays 23, 46 and 45 operate as before but relay 38 closes in place of relay 37, thus sending a 2-dot cardioid transmission in the opposite direction. Relay 45 serves to render antennas 26 and 28 inoperative during the cardioid transmission from antennas 25 and 27. I

, Fig. 3 shows a further application of my invention in which the cardioid transmissions take place in four diiferent directions instead of two. In this case, the cardioid transmissions take place along the direction of each antenna of the transmission line type'of antenna system, regardless of their orientation in space and the position of the beacon courses. The system is merely an extension of that shown in Fig. 1, two more cardioid transmissions consisting of 3 and 4-dot signals taking place at right angles to the two shown in Fig. 1.

In Fig. 3: 1, 2, 3 and 4 represent the location of the vertical antennas of the transmission line type of system. 47, 48, 49 and 50 represent the radio beacon courses. 51 represents the cardioid transmissions in the direction of antenna 1; 52 represents the cardioid transmissions in the 1}- rection of antenna 3; 53'represents the cardioid transmission s'in the direction of antenna 2, and 54 represents the cardioid transmissions in the direction of antenna 4.

Fig.- 4 is a circuit for sending the dot and 2-dot cardioid signals as shown in Fig. 2 and, in addition, the 3 and 4-dot cardioid signals, thus Relays producing the four cardioidsshown inLEig..3.. .In 'Ayfurther. application of my invention isthat I the circuit, 17is a;motor foridrivingardotiscoding wheel 48; 47is apslip ring: for making: contact with segments 53,254, 55 and .56." 49, 50, 51: and

52 are brushes making: contact with? segments .56,

55, 54,andx53,.respectively. 5.7 isxthe 'dotimaking contactor. 23is;a:double-pole, double-throw re.

lay connectingeither the-65 cycleand 86% cycle modulation -or the 1000 cycle 1 to the beaconamplifiers through transformer 24, 25, 26, 27 and 28 are the verticalantennasiof, the transmission line type of antenna system. 129, 30, 31 and 32 are mission. lines when sendingthe ca'rdioid.v signals.

65and 46 are closed circuit doublerpolavsinglethrow relays [for disconnecting ,the radiO-fre;

i quency supply from the center of the transmission line when sendingthe cardioids and 64. and 45 are single-pole, single-throw shorting relaysfor rendering the antennas. inoperative in.the set of antennas not transmitting cardioids during; a

givenset oi dotjtransmlissionsi. 33, 34, s; 59, 35,

36, 6i and 62 are sectionsot the phasnigsections' which are thrown intodifierent partsof the trans mission lines by relays 3'7, 60, 38 and '63 when sending the cardioidsi 43 and 44 are the sec- 1 ondaries supplying the-Jradio-frequency" to an- .tennas 26- 28 and; -27, respectively, from sources of energy 43aand 44a;-respectively. This system operates similar to that described under Fig. 2 exceptthatlbrushes 49, 50, 51 and 52 select the proper .set: of *relaysforrse'nding the, cardioids' in the four different directions. When. brush 49 Contact wheel 22 serves tosend the setof cardioid signals as often as desired. V

In cases where itis necessary to send. cardioid transmissions in directions other than along the 1 line of the transmis'sion-dinetype of. antenna systems, it is necessary to simultaneously radiate two cardioid signals oi the properphase and amplitude from both antenna system's giving a resultant -at-an angle to the line of direction of the transmission line type of antenna system: A method of accomplishing this is shown in Fig.5. This differs from Fig. 4 only in that'contact wheel 66 has, a difierent arrangement of seg-a ments so that when 5'7 closes to ,makeone dot, 49 and 50 touch segment 70,.operatingboth. relays 37 andGO, as well as 23,65 and 46, producing a resultant cardioid in a direction at; say;

degrees toantennas 25 and 26. When 57 closes to make-2 dots and and 51 touch 69, relays and 38 operate as well as 23; and 46,producing a resultant cardioid at, say, 45 degrees to antennas 26 and 27. 3 dots and 51 and 52 touch 68, relays38 and 63 operateas well as relays 23, 65 and 46, producing a resultant cardioid at, say, 45 degrees to antennas 2'7 and 28. When 57 closes to make 4 dots and 49 and 52 touch, 6'7, relays 63 and 37 operate as well as relays 23, 65 and 46, producing a resultant cardioid at, say, 45 degrees to antennas 28 and 25.

When 47 closes to make it'enables a pilot to determine when he has passed over the beacon,..which'is of considerable help as it gives him a definite fixf. Referring to Big. 3, assume a pilot to be flyingnortheast along course 47; He hears I dot very loudly and 2 dots very weak until he passes over the beacon on to course 49 thenthe 1 dot becomes weak and the 2 dotsloud, indicating to him that he has passedover. the beacon. Thisis the case with anyone of the-.4 courses. For example, when flying south on. course 48, 3 dots will be heard very. loudly until thebeacon is passed, and then 4.dots will be heard very loudly on course 50.

It is understood that while the transmission line type of beacon antenna system has been shown: this invention is not limited in its appli,- cation to that type, but any form of antenna system may be used producing beacon courses of the aural or visual type in fixed directions, the unidirectional transmissions for the quadrant 'or course identification being, obtained either from the beacon antenna system alone or this antenna system in combination-with other suit:

able. antenna systems. Thecrossed-loop beacon antennas in combination witha vertical antenna is an example of another workablecombination. In this case the relays would function to tune and excite'the vertical antennawith a radio frequency signal of proper phaseand amplitude when sending 1 the cardioids. i l i i It is also understood that: this invention is notlimitedto the transmission of the identifica tion signals during an interruption of the beacon course signals in the case of the visual type beacon giving courses of the double modulation signal typeyas such unidirectional identification transmissions may take place simultaneously on the same radio frequency with the beacon signal 1 transmissions, from a separateantenna system,

an audio-filter system being used on the receiver output to keep the identification signals from the visual course indicator. An advantage of this method is that the unidirectional identification transmissions could be sent continuously, the frequency of transmission being suchas to'require no wait on the pilots part. This is an advantage, especially when usingthe signal to determine when the beacon has been; passed over.

Itis further understoodthat while auralreception of the unidirectional. identification signals has been mentioned, the reception of these signals may be on a visual formof indicator if desired. i,

It is further understood that while mention has beenmade of sending adifierent coded signal in each of the different directions, that this invention is not limited to such a coded signalbut may include the same signal in all directionsof transmission but on" a different frequency of modulation. In this case, referring to Fig. 4, relay 23 wouldbereplaced by 4 relays eachin series respectively with relays 3'7, 60, 38, 63, each relay connecting a ,difierent audio frequency on transformer24. The 2, :3 and 4 dots on code wheel 48 would each be replacedby a single dot or dash. While I have described and illustrated difierent examples of my invention, I do not wish to be limited to these specific examples since modifications may be made both in the circuits and apparatus within the scope of my invention.

What I claim is: l

l. A radio-beacon comprising means for transmitting range course signals in definite directions,means for interrupting the beacon course signal at suitable intervals, means for transmitting during the complete interval of inter-. ruption a series of unidirectional transmissions in different directions each of said transmissions being differently coded.

2. A radio beacon comprising means for trans mitting beacon course signals and aseries of unidirectional signals. in definite directions, means for interrupting the beacon course signal at'suitable time intervals and permitting the transmission during said intervals of interruption' of the series of unidirectional transmissions in different directions from said radio beacon, each of said transmissions being differently coded.

3. A radio beacon, comprising means for transmitting range course signals of the double modulation visual type providing fixed course signals at definite angles, means for transmitting differently coded unidirectional signals at definite angles, four vertical antennas arranged in substantially opposing pairs for radiating said signals, each antenna being energized from said transmission means through a transmission line, a plurality of two position relays connected to phasing sections in the said transmission lines and to the said means for transmitting range course signals and said means for transmitting the differently coded unidirectional signals, and automatic code means operating said relays for producing the said fixed courses when in one of said positions and the said differently coded unidirectional signals when in the second of said positions. a

4. A radio beacon of the double modulation type comprising means for transmitting range course signals at definite angles and including an antenna array having four vertical antennas arranged in substantially opposing pairs, non-radiating transmission lines supplying diagonally opposite antennas, sources of radio frequencies, one for supplying one of the transmission lines of diagonally opposite antennas, relays for connectingsaid source of radio frequency with said transmission lines and to change the phase of the currents in the antennas, andanother relay for changing the modulation of the current in said transmission lines, and a code signal means electrically connected With said relays for operating the same whereby certain of the loading sections in the transmission lines are connected in one position of the relay and disconnected with other loading sections in one position of the relays, said relays being so arranged that the loading sections, when in said transmission line, are sufficient to produce a unidirectional transmission from a given set of said two antennas. a

5. A radio beacon of the aural type comprising means for transmitting range course signals in definite directions, means for interrupting at suitable intervals the beacon signals producing said courses, means for transmitting from the beacon antenna system during said interruptions a series of unidirectional radio transmissions in different directions, each of said transmissions being differently coded such that they maybe differentiated.

' 6..A. radio beacon of'the doublemodulation type comprising means for transmitting range cou'rsesignalson a given carrier frequency and means for transmitting on the same carrier frequency, but different modulation, unidirectional signals at definite angles, an antenna system for the transmission of said course signals, a second antennasystem radiating the unidirectional transmissions indifferent directions, said unidirectional transmissions being differently coded in each of said difierent directions 'andtrans mitted simultaneously with said course signals;

'7. A radio beacon of the visual type comprising means for transmitting range course signals in definite directions, means for radiating from the beacon antenna system a series of unidirectional radio transmissions in different directions, and modulated at a difierent audio frequency in each .of said different directions, and means for interrupting the range course signals only for the period of each of said unidirectional transmissions.

8. A radio beacon of the aural 'typecompris- 7 ing means for range course signals in definite directions, means for radiating from the beacon antenna system'a series of unidirectional radio transmissions in different directions, and modulated at a different audio frequency in each of said different directions, and means for interrupting the beacon course signals for the period of said'unidirectional transmission.

'9. A radio beacon of the double modulation type comprising means for producing fixed range course signals at definite angles and including an antenna array having four vertical antennas arranged at the corners of a square, non-radiating transmission lines supplying each diagonally opposed antenna with the said beacon course signals, means for producing unidirectional signals including a circuit and a 1, 2, 3 and 4-dot code wheel and contactor therefor in said circuit, twoposition relays in said circuit and operated by said code wheel, said relays connecting certain loading sections in said transmission lines in one of said positions and disconnecting certain other said loading sections in their second said position, said loading sections when in said transmissionlines being sufficient to produce the unidirectional code signal transmission in different directions from a given set of two of said antennas and each coded with a different number of dots in each of said different directions.

10. A radio beacon of the visual type comprising an antenna system, means for radiating from saidantenna fixed double modulation range course signals in definite directions on a given carrier frequency; and means for radiating simultaneously from said antenna system, on the same carrier wave but on different modulation, unidirectional signals at definite angles and differently coded in different directions, respectively.

FRANCIS W. DUNMORE. 

